Voltage regulator



Jan. 16, 1934.- L, A, HYLAND 1 1,943,320

VOLTAGE REGULATOR willed Jan, e, 1932 A TTORNEY .Patented Jan. 16, 1934 VOLTAGE REGULATOR Lawrence A. Hyland, Washington, D. C., assigner by mesne assignments, to Eclipse Aviation Corporation, East Orange, N. J., a corporation of New Jersey Application January 6, 1932. Serial No. 585,012

6 Claims.

(Cl. P11-119) (Granted under the act of March 3, 1883, as

amended April 30, 1928: 370 O. G. 757) The present invention is a continuation in part of the invention disclosed in my co-pending application, Serial No. 382,371, filed July 31, 1929, for Electrical apparatus, and relates to directl current generators generally, and more particularly-to the voltage regulation Aof such generators.

, In all direct-current generators, voltage regulation is somewhat of a. problem, but nowhere are l the requirements for such regulation so stringent and the operating conditions so severe and critical as when a generator is to be used for radio purposes on aircraft, where the generator is always driven either by a propeller or by the engine of the craft. In either case, the speed of the generator varies widely with consequent variations or changes in the voltage output of the generator.

The present known methods for voltage regulation of direct-current generators driven at variable speeds employ either electro-mechanical or thermionic means. Such means, however, require comparatively long intervals for their action with the result that over-regulation and underregulation is produced and the range of regulation is rather limited and consequently the current, instead of being smooth and unvaryingis pulsating and irregular. Accordingly, one ci the objects of the present invention is to provide a novel voltage regulator whereby the foregoing dimculties are eliminated.

Another object is to provide a novel electrical control system for regulating the output voltage o! a direct-current generator.

Another object is to provide a novel electrical generating system whereby the generated potential is substantially constant.A

Another object is to provide a novel electrical generating system particularly adapted for use in energizing a radio signaling system, whereby the energizing potential is substantially constant.

A stillfurther object o1' the invention is to provide a direct-current generator, the voltage of which is substantially independent of variations in the speed of said generator.

The above and otherl objects and advantages of the invention will appear more fully hereinafter from a consideration ci' the detailed description 50 which follows, taken together with the accompanying drawing, wherein isillustrated one em-' bodiment of the invention.' It is to be expressly understood, however, that the drawing is only for the purpose of illustration and description,

and is not designed as a definition of the limits of the invention, reference being had for this purposefto the appended claims.

In the drawing,

Fig. 1 is a schematic circuit diagram of one arrangement embodying .the present invention;

Figs. 2 and 3 are graphical representations of the operating characteristics of the invention; and

Fig. 4 is a graphical representation of variation of excitation current in the auxiliary iield coil 35 with the frequency of the alternator.

Referring to Fig. 2 of the drawing, there is shown a graphical representation of the variation of the voltage output of the usual' type of direct-current generator with the speed of rota- 7. tion thereof.' The speed is indicated as R. P. M. which is plotted along the horizontal axis, and the potential output of the usual type of generator is indicated by the solid curve e. The potential output of a generator controlled in accord- 7| ance with the invention may be indicated by the dotted line e. The graph shows how the output potential e of the usual generator varies with the speed of rotation and how the output potential e of the generator system of the present invens tion is controlled within said deilned limits.

The voltage regulation of the direct-current generating system embodying the present invention is accomplished in a manner sin/iler to that disclosed in my above-referred-to cci-pending application Serial No. 382,371, wherein the output voltage of an alternator is maintained substantially constant by varying the field excitation of the alternator in inverse proportion to the frequency of said alternator, which varies directlv as the speed thereof. To ths end, the directcurrent generator of the present arrangement is drivably connected with an alternator and both are driven by a variable prime mover, such as an air propeller, and the eld excitation of the direct-current generator is controlled from the output of the alternator in inverse proportion to the lfrequency of the latter. As hasbeen pointed out in the above referred-to co-pending application, it is possible to control the output oi an alternalo. tor by controlling the exciting energy thereof, and in- Fig. 3 oi the accompanying drawing is shown a graph indicating roughly the control obtained in the voltage regulator embodied in the present invention by controlling the ileld excitation of the direct-current generator from the output of the alternator. The horizontal axis represents the frequency of the alternator, which is directly proportional to the speed oi'said; alternator.

vFor the purpose of illustrating the operation, no

' ondaries 13 and 14 are connected to the ends of it will be assumed that the frequency at the normal speed of the alternator is f-i-. The output potential of the direct-current generator is designated by the horizontal line E. The resultant eld excitation of the generator is designated by the dotted line It is seen that the resultant field excitation p increases as f-l-:r approaches f; and as the speed of the generator and therefore the frequency of the alternator increases, approaching the value f+:ri, the resultant field excitation reduces in value. As the output potential of the alternator would normally increase as the speed is increased then, by accordingly and simultaneously decreasing the resultant eld excitation of the generator with the increase of speed, the output potential of the generator will remain substantially constant. This is accomplished as illustrated schematically in Fig. 1 of the accompanying drawing.

Referring to Fig. 1, the direct-current generator shown is of the shunt type embodying an armature 4 which revolves adjacent to the magnetic field produced by the shunt field winding 5, thereby generating a current feeding into any suitable load 6 which, as pointed out above, may be the high potential circuits of a radio signaling system. On the same shaft with thearmature 4 is a rotor '7 of an inductor alternator having a field winding 8 connected in parallel with the field winding 5 of the direct-current generator, and an armature winding 9. The inductor alternator is preferably of a size such that the power generated therefrom is a relatively small proportion of the power supplied by the main directcurrent armature 4. Y

The alternator armature 9 is connected to a primary winding 10 of a transformer 1l, and shunted across the primary 10 is a condenser 12, which operates to tune circuit 10-12 so that by reason of the phenomenon of parallel resonance, a certain critical frequency will be rejected by the circuit 10--l2, while other frequencies will be passed through the secondaries 13 and 14 of the transformer 11. The secondary 13 supplies the high tension current to the plates 15 and 16 of a full-wave thermionic rectifier 17, while the secondary 14 supplies current to the lament 18 of the rectifier. Since a certain amount of resistance will be present in the tuned circuit lll- 12, there will be a peak rejection at the frequency of resonance f and a gradual rise on either side with the greatest amount of current passed at frequencies well away from the resonant frequency, as illustrated in Fig. 4. It is to be understood that any tuned circuit or means for obtaining the tuned circuit may be utilized for this purpose and the action of the tuned circuit may employ series resonance with peak acceptance. The action of the rectifier is largely dependent upon the Voltage supplied vby the amature 9-through the transformer 11 by reason of the tuned characteristics of said transformer. The mid-points of the transformer seca differential field winding 19 associated with the main field winding 5 of the direct-current generator so that the magnetic field produced thereby will oppose the field produced by the main fleld winding. By this arrangement, the total field excitation of the direct-current generatorwill be decreased as the generator speed increases, and vice Versa, because of the increase in current in winding 19 when the frequency increases and a decrease in' current when the frequency decreases, as will be explained more fully hereinafter. It is also to be noted that the alternating current from the rectifier adds to or detracts from the total fleld current in a manner to aid regulation. As pointed out above, the peaking or frequency adjustment of the transformer 11 is controlled by the frequency adjustment of winding 10 and condenser 12, which latter elements may be termed a filter.

Many other methods may be employed, as are well known to those skilled in the art, whereby an upper and lower cutting-off frequency characteristic is obtained. This is similar to what is known as the confluent of the bar-pass filtered design. The larger values of current delivered to coil 19 through rectifier 17 will occur when the frequency of the alternator is f-l-x or f-i-zi, which frequencies are higher than the frequency characteristics of primary winding 10, the latter frequency characteristic being designated as f. The value of 3:, which is the frequency difference between the normal frequency j+1: of the alternator and the frequency f of the transformer is properly chosen of a desired value.v As an illustration, f may be 400 cycles and f-l-:r 500 cycles, which makes :I: equal cycles. When the alternator frequency changes from 500 cycles to 400 cycles due to a decrease in speed, the energy in windings 13 and 14'is decreased when the frequency of energy from the alternator approaches the frequency of 400 cycles and hence a decrease in flux in the differential winding 19, as will be apparent from Fig. 4. This produces a higher value of resultant exciting energy of the windings 5 and 19 and hence counteracts a change of the voltage which would have occurred had the excitation energy remained constant. When the speed of the alternator increases, f+x1 being higher than j+1: and hence further from the-frequency characteristics f of the transformer the current in coil 19 is further increased and the resultant excitation of the field windings 5 and 19 isfurther reduced which counteracts the increase of voltage ordinarily ensuing with an increase of speed. The elements of tuned circuit 10-12 may be so selected and disposed with respect to their elec- 1 trical characteristics that any desired slope may be obtained of the curve of the field excitation current.

The frequency characteristics of the transformer 11 may be controlled by the design of windings 1U, 13, or 14, or of the core, or by providing tapped connections to the windings, variable regulation of a closed core, condensers across windings 13 and 14, or any other suitable means. It is preferable to provide the fundamental frequency characteristics of the transformer of lower value than the normal frequency of the alternator. As pointed out above, direct-current armature 4 may be associated with any desired load circuit represented at 6. There is thus provided a novel arrangement whereby it is possible to generate high potential energy, the voltage of which will be substantially constant with respect to any change that would normally be caused by variations from variation in the speed of the direct-current generator.

Many modifications of the present invention are possible without departing from the spirit thereof, and Figs. 3 and 4 are only for the purpose of illustrating the operation of the voltage regul 1t is not intended to restrict che embbdimenrs 150 of the invention by the frequency values chosen for purpose of explanation in the foregoing specil teristics may likewise be of any suitable design to operate on any desired frequency bar.. Any suitable type of rectifier may be employed instead of the thermionic tube 17 shown. Neither is it intended to restrict the embodiment of the invention through a shunt direct-current generator, since it is believed to be obvious that the arrangement may be adapted to control the output potential of other types of direct-current generators. Reference will therefore be had to the appended claims for a definition of the limits of the invention. y

The invention herein described may be manufactured 'andused by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon.

What is claimed is:

1. In a regulator system, a direct-current generator having a main field winding, an alternator drivably connected to and rotatable with said generator and having a field winding energized by the latter, the frequency of the alternating-current from said alternator varying directly as the speed of the generator, a rectifier connected to the output of the alternator, said rectifier having a tuned input circuit tuned to reject frequencies below the normal operating frequency of the alternator sor that -the output of the rectifier increases with the frequency of the alternator, and

means comprising a differential field winding in i opposed relation with the main field winding of the generator and connected to the output of the rectifier `for`causing an increase in the output current of said rectifier to produce a change in the field excitation of the generator inversely with the speed thereof for maintaining the output voltage of said generator constant.

2. In a regulator system, a direct-current generator having a main field-winding, an alternator drivably connected to and rotatable with said generator and having a field winding energized by the latter and in shunt with the main field winding of said generator, the frequency of the alternating-current from said alternator varying directly as the speed of the generator, a full-wave rectifier connected to the output of the alternator, said rectifier having a tuned input circuit tuned to reject frequencies below the normal operating frequency of the alternator so that the output of the rectifier increases with the frequency of the alternator, and means for causing an increase in the output current of said rectifier to produce a decrease in the field of the generator for maintaining the output voltage of said generator constant, said last named means comprising a differential winding connected to the output of the rectifier and opposing the main field winding of the generator.

3. In combination, a direct-current generator having a main field winding, an alternator drivably connected to and rotatable with said generator and having a field winding in shunt with the generator field winding, a rectifier connected to the output of the alternator, a tuned circuit between the alternator and rectifier and tuned so that the output of the rectifier increases as the frequency of the alternator increases due to increase in speed of said alternator and hence said generator, and means connected to and governed by said rectifier for varying the main field of the generator in inverse proportion to the output of the rectifier and hence in inverse proportion to the frequency of the alternator.

4. In combination, a direct-current generator having a main eld winding, an alternator drivably connected to and rotatable with said generator and having a field winding in shunt withA the generator field winding, a rectifier connected to the output of the alternator, a tuned circuit between the alternator and rectifier and tuned so that the output of the rectifier increases as the frequency of the alternator increases due to increase in speed of said alternator and hence said. generator, and means governed by said rectifier for varying the main field of the generator in inverse proportion to the output of the rectifier and hence in inverse proportion to the frequency of the alternator, said last named means comprising an auxiliary field winding for the generator connected to the output of the rectifier and arranged to oppose the main field winding thereof.

5. In a regulator system, a direct-current generator having a main field winding and an auxiliary field winding in opposition thereto, an,a.l`

ternator drivably connected to and rotatable with said generator and having a field winding energized by the latter, a thermionic rectifier tube having two anodes and a cathode, a transformer having a primary winding connected to the output circuit of the alternator and a secondary winding having its ends connected to the anodes and a mid-tap to one end of the auxiliary field winding, the other end of said auxiliary field winding being connected to the cathode of the rectifier, v

and the primary of said transformer being tuned bya condenser connected in shunt therewith to reject frequencies below the normal frequency of the alternator so that the output current from 4the rectifier increases with the frequency of the alternator, thereby increasing the field of the auxiliary winding directly with the speed vof the generator to produce changes in the resultant eld excitation of the generator inversely with the speed thereof for maintaining the output voltage constant irrespective of speed.

6. In a regulator'system, a direct-current gen'- erator having a main field winding and an auxiliary field winding in opposition thereto, an alternator drivably connected to and rotatable with said generator and havingl a separate field winding in shunt with the main field winding of the generator and energized by the latter, a thermionic rectifier tube having two anodes and a cathode, a transformer having a primary winding connected to the output circuit of the alternator and a secondary winding having its ends connected lto the anodes and a mid-tap to one end of said auxiliary field winding, the other end of said auxiliary field winding being connected to the cathode of the rectifier, and the primary winding of said transformer being tuned by a condenser connected in shunt therewith to reject frequencies below the normal frequency of the alternator so that the output current from the rectier increases with the frequency of the alternator thereby increasing the field of the auxiliary winding directly with the speed of the generator to produce changes in the resultant field excitationv of said generator inversely with the speed thereof for maintaining the utput voltage constant irrespective `of the spee LAWRENCE A. I'IYLAND. 

